ubi_leb_read(9)

💜 ubi_leb_read(9) — like, the kernel API manual, bestie 💜

okay so this is ubi_leb_read from the Kernel API Manual and honestly? it's giving "small function, big responsibilities" energy. sit down, grab a strawberry 🍓, and let's get into it.

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✨ NAME ✨

ubi_leb_read — reads data. that's it. that's the whole vibe. reading. data. slay. 💅

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🌸 SYNOPSIS 🌸

int ubi_leb_read (struct ubi_volume_desc *desc , int lnum , char *buf ,
       int offset , int len , int check );

like, copy that exactly or the compiler will absolutely humble you 😭

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🎀 ARGUMENTS 🎀

• desc — the volume descriptor. your ticket to the volume, no cap 🎟️
• lnum — the logical eraseblock number you're reading from. which LEB, bestie.
• buf — the buffer where the read data gets stored. this is where the good stuff lands 🫶
• offset — the offset within the logical eraseblock to start reading from.
• len — how many bytes to read. the amount. the quantity. the length 💅
• check — whether UBI has to check the read data's CRC or not. yes/no energy.

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🦋 DESCRIPTION 🦋

so the way this works: this function reads data from offset of logical eraseblock lnum and deposits that data all cute and cozy at buf. ✨

now here's the tea on static volumes ☕ — when you're reading from a static volume, check is the flag that decides whether the data actually has to be checked or not. if yes, the whole logical eraseblock gets read and its CRC checksum gets verified (iykyk: the CRC checksum is per-eraseblock, one per block, that's the rule). so like, checking can substantially slow down the read speed 😭 — genuinely, it's not cheap. and for dynamic volumes, the check argument is just ignored entirely. it's giving "not my business, not my problem" 🙈

on success? this function returns zero. iconic. on failure? it hands you back a negative error code. 💀

here's when you get -EBADMSG:

• for both static and dynamic volumes — if the MTD driver has detected a data integrity problem (that's an unrecoverable ECC checksum mismatch in the case of NAND) 😬
• for static volumes — in the case of a data CRC mismatch ⚠️

and if the volume is damaged because of an interrupted update? this function just returns immediately with the -EBADF error code. no drama, no waiting around, just vibes and an error return 🫠

fr fr, notice that -EBADMSG can hit dynamic volumes too — it's not just a static-volume thing. don't get caught lacking.

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🔥 SEE ALSO 🔥

the kernel file is ./drivers/mtd/ubi/kapi.c — that's where the magic lives, go be nosy 👑

• ubi_do_get_device_info(9)
• ubi_get_device_info(9)
• ubi_do_get_volume_info(9)
• ubi_get_volume_info(9)
• ubi_open_volume(9)
• ubi_open_volume_nm(9)
• ubi_get_num_by_path(9)
• ubi_open_volume_path(9)
• ubi_close_volume(9)
• leb_read_sanity_check(9)
• ubi_leb_read_sg(9)
• ubi_leb_write(9)
• ubi_leb_erase(9)
• ubi_leb_unmap(9)
• ubi_leb_map(9)
• ubi_is_mapped(9)
• ubi_sync(9)
• ubi_register_volume_notifier(9)
• ubi_unregister_volume_notifier(9)

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and that's the whole page, bestie 🧚✨

cute little sign-off: this one lives at ./drivers/mtd/ubi and it's dated October 2026 — yes, the future. main character energy only 🌈👑💖